Hyundai Repair: 1999 Hyundai sonata with a hesitation problem, hesitation problem, hyundai sonata

Question
My Sonata does not always respond when I step on the gas, and seems to "misfire" especially at speeds above 45 mphs.  After driving above 45 and slowing to a stop it chugs like it is going to quit.  I've had the transmission and fuel pump looked at, but they can't seem to find the problem.  Do you have any suggestions?  Any input is much appreciated.  Thank you!

Answer
Your description certainly makes it sound like you have a misfire.  

Is your check engine lamp on?  Most misfires will set a check engine lamp.  If it is on, you should start with reading the engine and transmission diagnostic trouble codes (DTCs).  AutoZone and AAMCO have advertised they'll do this for free.

Most misfires are caused by secondary ignition components.  If you indeed have a misfire, I'd recommend starting with checking your plug wires, plugs, and ignition coil.